When choosing to buy memory foam you would normally come across a large variety of these in all shapes, sizes, weights or density etc. With a wide range of choices to make it becomes rather difficult to make choices. So here is what you need to know on how they are graded and this understanding will help you make find exactly what you need.
Categories for the grading system
Memory foams are graded on their density in terms of its weight in pounds per square foot. Higher density results in greater visco-elasticity from having more of its chemical components packed into a smaller area.
Better visco-elasticity implies greater life of the memory foam unique property. Recommendation density is about 4-5lb. Although density is a good measure of the quality of the memory foam but it alone does not give a complete picture.
This is another grade that should be taken into consideration while deciding on a purchase. IDL stands for Indentation Load Deflection. Without getting into the details of this grading system, IDL simply rates on how soft or hard the memory foam is.
A higher IDL rating implies that the foam is firmer or harder. When considering IDL ratings always take in to consideration the thickness of the memory foam. Thicker foams can make do with lower IDL ratings and vice versa.
Resilience and Tensile strength rating
Although they not as important as density and IDL rating from a buyerâs point of view, resilience and tensile rates gives an overview of the durability and quality of the foam. Higher resilience rating implies greater rebound and accordingly stronger and more durable foam when exposed to pressure.
Simply put resilience determines how long the memory foam will keep returning to its original shape. While tensile strength determines the ability of the memory foam to handle stretching or compression.
This is not exactly a grading system but it is very useful in getting an overall idea on how good the quality of the memory foam is. Generally the warranty on good quality foams should range between 10 â 30 years. Any memory foam with a warranty of below 10 years does not speak well for itself while a warranty of 15 years is highly recommended for purchase.
Overall memory foam grading rates are not exact as it can vary from the marked ratings. For example an IDL rating of 35lb can show variations in range of 34 to 36.